The long term objective is to develop an anesthesia delivery system with monitoring, alarm and control capabilities so that 1) closed circuit anesthesia can be performed as easily as the semi-closed high flow procedure presently is and 2) the anesthesiologist's awareness of the state of the anesthesia and the anesthesia equipment is improved for both the closed and semi-closed circuit procedures. The specific aims are: 1) develop a digital valve/vaporizer system for precision delivery of anesthetic gas, 2) design and implement a microcomputer based control system for automatic control of inspiratory anesthetic gas concentration and 3) develop an intelligent alarm system for detection of anesthesia alarm states. During Phase I, a stainless steel version of the digital valve will be constructed and tested together with a heated copper coil vaporizer. The valve will be tested for long term reliability liquid pulse delivery accuracy and its behavior after anesthetic preservative film deposition. The vaporization system will be tested for bias gas flow (02, N20) requirement and the heat flux required for the maximum vaporization rate required. In Phase II, the system will be assembled, control and alarm software written and then tested in animals and subsequently humans.